CACTUS-SHAPED MIMO ANTENNA

Introduction

MIMO antennas needed for high data rate wireless communications

Proposes a dual-band cactus-shaped MIMO antenna for wireless &

satellite apps

Single Antenna Design

Cactus shape formed by T-shaped radiator and two inverted-F

branches.

Operates in 4.9-5.45 GHz and 8.72-11.55 GHz bands.

T-shape radiator induces lower frequency band, F-branches give

higher band.

MIMO Antenna Geometry

Two cactus antenna elements with 0.12λ edge-to-edge spacing.

Inverted U-shaped decoupling structures on ground plane.

Ladder connection between decoupling structures

Results & Discussion

Good impedance matching below -10 dB in both bands.

High isolation of >20 dB between MIMO elements

Stable antenna gains around 3-4 dBi across both bands.

Omnidirectional radiation patterns suitable for wireless

communications

Conclusion

Compact cactus MIMO antenna covers wireless and satellite bands.

Decoupling structure minimizes mutual coupling for good diversity.

Could enable high data rate multi-band wireless communications.

ROUTING ALGORITHMS FOR FLYING AD-HOC NETWORKS (FANETS)

Introduction

FANETs consist of unmanned aerial vehicles communicating with

ground stations

Node mobility and changing topology make routing challenging

Nature-inspired algorithms (NIAs) promising for FANET routing

Existing Algorithms

Ant colony optimization (ACO) - mimics ant colony behavior

Firefly algorithm (FA) - based on flashing light attraction of fireflies

Genetic algorithm (GA) - uses natural selection and genetics

Modified Algorithms

Modified FA (MFA) - adds clustering of nodes

Modified GA (MGA) - uses location-based mobile coverage

Simulation Setup

Algorithms: ACO, MFA, MGA

Simulator: ns-3.26

Parameters: packet delivery ratio, delay, overhead, throughput

Results

MFA has best performance on all metrics

ACO second best after MFA

MFA and ACO show most promise for FANET routing

Future Work

Enhance ACO and other NIAs for better FANET performance

Develop new bio-inspired routing algorithms

In summary, modified firefly algorithm performs the best for routing in

flying ad-hoc networks based on simulations. Further improvements to

swarm intelligence algorithms could enable more efficient FANET

communication.

THE QUAD-BAND ANTENNA WITH CIRCULAR POLARIZATION

DIVERSITY

Introduction

Multi-band antennas with polarization diversity useful for many

wireless systems

Proposes a quad-band antenna with linear and circular polarization

diversity

Antenna Design

Based on a monopole antenna with L-shaped and slotted radiators

Generates 4 impedance bands from 3-15 GHz

Modes studied using characteristic mode analysis

Performance

Achieves left-hand circular polarization (LHCP) in bands 1 and 3

Linear polarization in bands 2 and 4

Good impedance matching, gain, efficiency and AR bandwidth

Circular Polarization Mechanism

Orthogonal modes with 90 degree phase difference

Equal amplitude orthogonal modes enable circular polarization

Current distribution varies over time to give LHCP

Radiation Characteristics

Omnidirectional patterns suitable for mobile applications

Reasonable axial ratio beamwidth obtained

LHCP in broadside direction, slanted due to asymmetric feeding

Conclusion

Simple quad-band antenna with linear and circular polarization

diversity

Could support diverse wireless applications requiring multiple bands

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